This invention relates to an assembly having interlocking sides. More particularly, the invention relates to an extrusion interlock assembly for joining two or more extruded pieces at an interlocking joint that may be slideably mated to produce an easily assembled and disassembled assembly.
Traditional techniques for housing and shielding electronic components typically employ sections of sheet metal or plastic formed in convenient shapes and fastened together by screws or other means. Such housings are generally known as miniboxes and are widely available to the public for non-critical needs. More expensive equipment, or equipment generating sufficient heat or radio frequency fields requires a more elaborate housing and typically utilizes a cast or extruded chassis to conduct heat away from sensitive electronic components. Covers may be secured to the chassis to provide mechanical protection and electronic radio frequency (RF) shielding. An example of such an electronic equipment housing may be found in U.S. Pat. No. 4,313,025, issued to Grube, Jr. Although each of the above examples are well suited to their application, a need exists for an inexpensive and easily constructed housing which provides mechanical and electrical integrity. U.S. Pat. No. 3,450,293, Seda, et al., offers one solution to the need. There, a box-like structure is formed from a collapsible side walls and interlocking joints. The joints may be further secured by screws or other fasteners which wedge flanges of equal inside radii and equal outside radii together to form a seal resistant to moisture. Such a structure, however, requires a relatively tight fit between interlocking joint flanges during assembly. This tight fit makes assembly difficult and leaves little room for undesirable burrs and chips to locate when the fastener is inserted into the interlocking joint.
Another solution is provided by U.S. Pat. No. 4,711,361, issued to Mischenki. There, the interlocking cover joint of an enclosure in which the inward curving edge of a first side having a first radius of inside curvature may be concentrically nested along the edge with an inward curving edge of a second side having a second radius of inside curvature unequal to the first. The first side of the housing also has a flange adjacent the inward curving edge and on the same surface as the inside curvature. This flange has a curved portion curved toward the edge and a lip portion at the end of the curved portion extending away from the edge. The second side of the housing has a lip and groove on the same surface as the inside curvature of the second side edge, the lip and groove shaped to received the lip portion of the flange. This approach leaves room for undesirable burrs and chips to locate when the fastener is inserted into the interlocking joint. However, the interlocking joint is still relatively intolerant of any misalignment from part tolerance or chips created during assembly. This is especially a problem when the first and second sides are extruded pieces, and are consequently prone to having large part tolerances.
Thus, it is apparent that improvements are needed in interlocking cover joints.